Dustin's Supercharged L67 Mods and Tune

Soooo I have a 98 Pontiac GTP with the L67 motor (122k miles), comes with a supercharger from the factory. Just going to do a few mods and tune to see what I can get out of the car. This is my first attempt at tuning. It's a cheap car so I figured it's a good one to try my hand at (except it's supercharged so might be a bit less forgiving and more complicated to tune)

Mods will be

-2000-2001 Stock GTP intake

-Cats removed and replaced with 3 inch downpipe/U-bend delete

-Autolight104 plugs (1 temp range colder), have a set of 103s also

-180deg thermostat.

-3.4 modular pulley swap (3.8 is stock)

-.5 volt alternator booster plug

Car will run on 91 but may make another tune on race gas just to experiment. No intercooler so might need higher octane to add much timing.

Don't really have any HP goals, just want to see what the best I can do is. Would be funny if I can beat my girlfriends 2014 Z4 (stock) but I think that may be a tall order since she is conservatively 300hp with the N54 motor.

Would like to baseline the car but don't really want to pay for dyno time although might call around just to get prices. I've heard some people have had great success with Harry's lap timer to check 1/4 mile times with a 10hz GPS.

Any suggestions/advice are appreciated. Probably start messing around with the car this weekend.